GPT-5.6 Sol and Luna: broader access to ChatGPT intelligence

According to OpenAI's announcement, GPT-5.6 Sol now powers ChatGPT Instant and deeper reasoning features for Plus and Pro users, providing more accurate and focused responses; GPT-5.6 Luna will provide unlimited text chat for Free and Go users starting tomorrow. The change makes the more advanced model more widely available, which could affect service quality and the user experience.